This article is the subject of a complaint and rebuttal from HE Dr Samuel Moncada, Venezuelan Ambassador to the UK. His full response can be found here.

Four decades ago, Richard Nixon was casting around for a new enemy to shore up support for his unique brand of uncompassionate conservatism. Having risen to national prominence as an anti-communist campaigner, then turned his attention to crime, he found a new foe in the counterculture.

The media were full of stories of clean-cut young men returning from Vietnam as wrecked junkies, while intellectuals such as Timothy Leary were promoting the use of LSD. So Nixon, elected on a wafer-thin margin and desperate to turn back the tide of permissiveness, declared war on drugs. "America's public enemy number one is drug abuse," he thundered.

While the Vietnam conflict has faded into history, thousands are dying and millions of lives are still being destroyed in his insane struggle. Fittingly, since it was launched by a president who turned out to be a crook, the biggest beneficiaries have been the most murderous gangsters on the globe as they rip apart country after country. Yet our leaders limp on in this self-defeating, $100bn-a-year war. Last week saw the latest salvo in the struggle when a host of distinguished names gathered under the banner of the Global Commission on Drug Policy to urge a truce. Their thoughtful report pointed out a series of obvious truths underlying how the war backfired so terribly and called for policies based on treatment rather than prosecution.

Look at the rise in drug use. In 1998, the United Nations committed member states to achieve a "drug-free world", pledging to eliminate or "significantly reduce" use of opium, cannabis and cocaine by 2008. Instead, global opiate use rose by more than one-third over that time, with big rises also for cocaine and cannabis. It is estimated almost 5% of the world's adults take illegal drugs.

Worse is the damage done by gangs fighting over the huge profits created by the illegality of this trade. We have all heard tales of headless bodies littering the landscape of Mexico. But the world's most violent region away from active war zones is further south – Guatemala and Honduras, for instance, both have more murders than the 27 countries of the European Union combined. Now the cancer is working its way through west Africa.

The trade is so lucrative that in several countries – some signed up to those sanctimonious UN pledges – drug gangs have bought or fought their way to power. Kosovo has a prime minister linked to drug smuggling, as are the leaders of Afghanistan, Burma, Guinea, Nicaragua and Venezuela. Then there are cases such as South Africa, where the police chief turned out to be the head of a crime syndicate.

There are so many arguments against current policies it is hard to believe anyone who is not stoned still signs up to Nixon's war. The vast costs, the crime waves, the racial dimensions, the stigmatisation, the futility. Then there is the dreadful hypocrisy of politicians who use and tax the lethal drug of alcohol then jail others who enjoy less damaging relaxants such as marijuana and ecstasy.

The key question is why? After all, we live in a world in which grandparents took acid or smoked pot while listening to the Grateful Dead and many parents were the people who dropped ecstasy at outdoor raves. The current occupant of the White House has confessed to taking cocaine, while several of our cabinet ministers admitted smoking weed. Drug use is no longer that big a deal, while it is clear many of the problems and much of the misery are byproducts of banning.

The Global Commission is a valiant effort, but it is noticeable that signatories include 11 former presidents, politicians and diplomats, but just one in office – the Greek prime minister, who presumably needs any extra revenue he can find. This is the fundamental problem: serving politicians lack the bottle to take the obvious remedial actions.

As the report rightly states: "Political leaders and public figures should have the courage to articulate publicly what many acknowledge privately: that the evidence overwhelmingly demonstrates repressive strategies will not solve the drug problem and the war on drugs cannot be won."

This failure of nerve is particularly acute in Britain. One cabinet minister who has admitted smoking cannabis in his youth said politicians were scared to act, despite knowing they should, since they would be slaughtered by rivals and the media for every drug-related death following liberalisation. "You may think it is absurd regulation and it may cost more lives but deregulation is impossible in our political climate."

Sadly, he is right. Witness the infantile response – especially from local Labour parties, as the campaign group Transform will testify – to any politician standing for election who has dared suggest saner drug laws. They should listen to the admirable Bob Ainsworth, who had a Damascene conversion while a home office minister: "The public are in a far more progressive place on this issue than most politicians and sections of the press."

Recent polling proves he is correct. One survey last year found 70% of Britons favoured the regulated sale of cannabis, with smaller majorities supporting legally available heroin, ecstasy and cocaine. Curiously, the groups most in favour were Conservative voters, middle-aged women and readers of mid-market tabloids. And just think how tax proceeds would help the public spending crisis.

Politicians say they fear drug use would rise if prohibition is lifted. Evidence from abroad shows they are wrong. Look at Scandinavia, where the tough Swedes and more liberal Norwegians have similar addiction rates. Or Switzerland, where heroin demand and crime fell sharply following new policies based on public health rather than legality. Or Portugal, where heroin use fell by half after decriminalisation.

These are places where there have been tentative steps forward. There are even signs the US, which remains the bastion of bigotry on this issue, is slightly shifting its stance under Barack Obama. It has, for example, permitted its blood-soaked neighbour Mexico to loosen cannabis laws.

Meanwhile, the tone of debate in Britain serves only to highlight the immaturity of our public discourse, with too many politicians lost in the fog of this foolhardy war. So here is a suggestion for our three main party leaders, who are all young enough to know better: why not hoist the white flag and work out a unified way to end a struggle that does so much more harm than good?

The alternative is to carry on fighting like generals in the First World War, ignoring the deaths, the devastation and the wastelands created around the world in a battle than can never be won.